Caffeine removal using activated biochar from acai seed (Euterpe oleracea Mart): Experimental study and description of adsorbate properties using Density Functional Theory (DFT)

Author(s)

Almeida, Arthur da Silva Vasconcelos de ^[1] ; Vieira, Wedja Timoteo ^[1] ; Bispo, Mozart Daltro ^[1] ; de Melo, Samara Farias ^[1] ; da Silva, Thiago Lopes ^[2] ; Balliano, Tatiane Luciano ^[1] ; Adeodato Vieira, Melissa Gurgel ^[2] ; Soletti, Joao Inacio ^[1]

Affiliation

^[1] Univ Fed Alagoas, Lourival Melo Mota Av S-N, BR-57072970 Maceio, AL - Brazil

^[2] Univ Estadual Campinas, Albert Einstein Av 500, BR-13083852 Campinas, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING; v. 9, n. 1 FEB 2021.
• Web of Science Citations: 0

Abstract

Alternatives for the use of acai seed have been investigated to remove caffeine from aqueous solutions. The pyrolytic process was conducted under two temperatures and heating rates (400 degrees C, 10 degrees C min(-1) and 600 degrees C, 50 degrees C min(-1)), with a vacuum pump coupled operating at 20 kPa and the biochar was activated with K2CO3, resulting in CA-SA 400/10 and CA-SA 600/50. Density, moisture, volatile and ash content were evaluated for biomass, as well as their activated carbons were characterized through elemental, thermogravimetric (TGA) analysis, N-2 adsorption and desorption isotherms (BET/BJH), infra red spectroscopy with Fourier transform (FTIR), X-ray diffraction (DRX), scanning electron microscopy (SEM), dispersive energy spectroscopy (EDS) and by the pHZPC method. CA-SA 400/10 and CA-SA 600/50 showed high values of specific area (1150.4 and 929.3 m(2). g(-1)), average similar pore diameter (2.55 and 2.66 nm) and a mixture in the structure between amorphous phase and graphitic. The adsorptive study showed that the pseudo-second order model adjusted better to the kinetic data and that intraparticle diffusion is not the only step that limits the process. Quantum chemical parameters were evaluated for caffeine, based on the Density Functional Theory (DFT) calculations, in order to understand its chemical reactivity at the atomic level. The results showed that the use of activated charcoal from acai seed is a promising material for removing caffeine, and emerges as an innovation for using the tailings. (AU)

• FAPESP's process: 19/11353-8 - Brazilian Water Research Center (BWRC)
• Grantee: Lauro Tatsuo Kubota
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 16/05007-1 - Removal of residual drug in aqueous solution by alternative adsorbents
• Grantee: Meuris Gurgel Carlos da Silva
• Support Opportunities: Regular Research Grants